Method and apparatus for applying adhesive attaching tapes to pads

ABSTRACT

Method and apparatus for applying adhesive attaching tapes to pads, such as diapers, in which an elongated strip of adhesive tape having an adhesive face and a non-adhesive back is folded longitudinally about a hinge line to form tape wings having their non-adhesive backs together and their adhesive faces facing away from each other. A release liner is applied to the adhesive face of one of the wings, leaving the adhesive face of the other wing exposed. Discrete folded tape segments are severed from the folded strip and are transferred from the vicinity of the severing tool to the vicinity of the pad by drawing the lined wings of the folded tape segments by vacuum against a vacuum drum. The adhesive face of the exposed wing faces outwardly of the drum. The drum is rotated to adhere the adhesive face of the exposed wing to a portion of the pad in the course of drum rotation. The lined wing is then free to have the liner stripped therefrom and unfolded about the hinge line for application of the exposed wing to another portion of the pad.

BACKGROUND OF THE INVENTION

Present techniques for applying attaching tapes to pads such as diaperseither do not locate the tapes advantageously with respect to the pad orinvolve production bottlenecks. Copending U.S. patent application Ser.No. 196,118 filed Nov. 5, 1971, now U.S. Pat. 3,772,120, discloses atechnique utilizing a vacuum drum which efficiently applies tapes topads, but does not locate the tape on the pad to achieve the advantagesof the present invention.

SUMMARY OF THE INVENTION

In accordance with the present invention, a rotary vacuum pad isutilized to apply tape segments to diapers or like pads and by whichsaid segments are advantageously located on the diaper pad in such a waythat the adhesive side of the tape segment at both ends of the tape isadhered to the plastic backing of the diaper. The tape segment isadhered to the outside face of the diaper pad and is hence protected bythe pad thickness from exposure to dampness.

In accordance with the present invention, a folded tape segment istransferred from the vicinity of a severing tool to the pad by means ofa rotary vacuum drum to which the lined wing of a folded tape segment isheld by vacuum with the exposed adhesive face of the other wing facingoutwardly therefrom. The tendency of the exposed wing to spring awayfrom the lined wing about its hinge line is overcome during the courseof rotation of the drum for example, by the impingement of an air blastagainst the exposed wing as the drum is rotated. An alternativetechnique is to use a guide rail which mechanically prevents the exposedwing from springing away from the lined wing. Moreover, aspring-actuated blade is desirably employed to hold the wings togetherbeyond the point at which the tape segment is severed and until the tapesegment is under the influence of the tape guide.

Other objects, features and advantages of the invention will appear fromthe following disclosure.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side view of apparatus embodying the invention.

FIG. 2 is a diagrammatic top view of apparatus shown in FIG. 1.

FIG. 3 is an enlarged detail view showing the relationship of the rotaryknife drum and the vacuum drum.

FIGS. 4, 5 and 6 are sequential views showing successive positions ofthe rotary knife and vacuum drums in the course of the coactiontherebetween in which the knife will sever a tape segment from the tapestrip and the segment is transferred from the vicinity of the knife tothe zone of influence of the air guide.

FIG. 7 is a perspective view illustrating the folding of the tape stripabout a tape folder blade.

FIG. 8 is a fragmentary detailed view illustrating the manner ofcoaction between the curved knife and the drum anvil to shear cut thetape segment from the tape. This view is taken along the line 8--8 ofFIG. 5.

FIG. 9 is a perspective view illustrating the manner in which the tapesas applied to the pads are utilized to attach a diaper pad to a baby.

FIG. 10 is a cross section along the line 10--10 of FIG. 2.

FIG. 11 is a cross section taken along the line 11--11 of FIG. 1.

FIG. 12 is a fragmentary perspective view showing a folded tape segmentadhered by vacuum to the vacuum drum.

FIG. 13 is a perspective view of the knife, per se.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention which may be embodied inother specific structure. The scope of the invention is defined in theclaims appended hereto.

A continuous web or strip of composite, relatively thick workpiece padmaterial 15 may be unwound from a parent roll 16 generally on the pathdiagrammatically illustrated in FIG. 1. Ultimately, the web 15 will besevered into discrete workpiece pad segments 13 used as diapers or thelike. In the case of a diaper 13, it is typically formed about a baby inthe manner illustrated in FIG. 9. Diaper 13 typically comprises an outerplastic film backing ply 78, a pad filler (not shown) and an innernon-woven fabric ply 79, as shown in FIG. 9.

Prefolded attaching adhesive tape tab segments 17 are applied toopposite side margins of the pad web 15, as it travels on its path shownin FIG. 1, by a pair of vacuum drums or rotors 18, 19, one for each sidemargin of web 15. Drums 18, 19 function to transfer the folded tapesegments 17 from the vicinity of rotating severing tools 20, 21 to theundersurface of the web 15.

FIGS. 1 and 7 illustrate the unwinding from parent rolls 24 of tworelatively wide strips 25 of adhesive tape, each having a non-adhesiveside 26 and an adhesive side 27. Each strip 25 is advanced to itsfolding blade or plow 28 which has an inclined edge 29 about which thestrip 25 is folded, as illustrated in FIG. 7, to form a U-shaped striphaving substantially flat wings 32, 33 connected on a hinge line 34. Thenon-adhesive side 26 of the tape is inside of the fold and the adhesiveside of the strip 25 is on the outside of the fold.

To effectuate the folding aforesaid, the tape strip 25 is passed betweenforming roller 35 which, as best shown in FIGS. 7 and 11, have enlargedend collars 36, 37 which space the roll surfaces 38 apart sufficientlyto receive the blade 28 therebetween and still leave room for the tapewings 32, 33 to fold about the blade 28 and to be guided thereabout bythe rolls 38. Rolls 38 are desirably provided with a Teflon or likecoating which is substantially non-adherent to the outwardly facingadhesive sides of the wings 32, 33.

As best shown in FIG. 1, a release tape liner strip 41 is applied to theexposed adhesive surface of one of the wings 32, 33 after tape 25 hasbeen folded and before the composite strip has reached its vacuum drum18, 19. The release liner strip 41 is so positioned as to be nextadjacent the surface of its drum 18, 19 when applied thereto, as is alsoshown in FIG. 12.

Each liner 41 is drawn off its parent roll 42 and is guided by guidingrolls 43 and against a pressure roll 44 for firm adherence to theadhesive tape.

Paired drive rolls 45 are actuated to feed the respective composite tapestrips around respective brush rollers 46 to a spring-biased idlerroller 47 which presses its composite tape strip up against the surfaceof its drum 18, 19, as illustrated in FIG. 3. Drums 18, 19 each containan anvil 48 which cooperates with a knife 51 on the rotating severingtool 20 for the purpose of severing the composite tape strips intodiscrete tape segments 17. The drums 18, 19 are provided in theirsurfaces adjacent anvil 48 with a vacuum pad comprising a pattern ofvacuum holes 52 (FIG. 12) connected by vacuum ducts 53 to a source ofvacuum, not illustrated, but which is conventional.

The rotating knife drums 20, 21 are mounted on axles 54 which areparallel to the axles 55 of the vacuum drums 18, 19. Knife blade 51 isprovided with a curved knife edge 56, as illustrated in FIGS. 8 and 13,so that when it presses the composite tape strip 25, 41 against anvil48, as illustrated in FIG. 5, the ends 57 of the knife will firstpenetrate the composite tape strip 25, 41 and the center portion or bow58 of the knife will engage the tape strip 25, 41 later on, thusproducing a shearing action of the knife 51 against the tape. Thisreduces shock and impact loads of the knife against the anvil.

Drums 18, 19 are rotated at a peripheral speed which matches the linealspeed of the pad web 15. The feed rollers 45 for the composite tapestrips 25, 41 are independently controlled so as to feed the prefoldedtape strips 25, 41 at a much slower speed. For each complete rotation ofdrums 18, 19, the feed rollers 45 advance short length of tape stripequal to the width of a tape segment 17 for each pad 13. Severed tapesegment 17 is advanced by its drum 18, 19 while the tape strip fromwhich the segment 17 has been severed slides on the drum periphery.Accordingly, the continuously rotating drum 18, 19 and coacting kniferoll 20 will sever tape segments 17 from the tape strip 25, 41 and willtransfer the discrete severed segment 17 from the vicinity of the knife51 to a location on the pad 15 opposite a pressure roller 61.

The internal construction of one of the vacuum drums 18 and knife roll20 is illustrated in FIGS. 3, 4, 5 and 6. The knife 51 is mounted on aninsert block 62 which is clamped by suitable apparatus in a cavityformed in the knife roll 20. As illustrated in FIG. 5, the knife 51coacts with the anvil block 48 in its drum 18, 19 to sever through thecomposite tape strip 25, 41. Prior to the coaction of the knife 51 withthe anvil 48, the feed rolls 45 have fed the strip 25, 41 far enough toadvance the tape segment 17 beyond the point of coaction of the knife 51and the anvil 48 and into a position over the vacuum nozzles 52.Accordingly, in the position of the parts shown in FIG. 5 where the tapesegment 17 has just been severed from the tape strip 25, 41, the segment17 is held onto the vacuum drum by suction.

Each knife roll 20 is also provided with a finger blade 64 whichperforms several functions with respect to the tape segment 17. Tapesegment 17 comprises wings 32, 33 folded about hingeline 34. Wing 33 towhich the liner strip 41 has been applied is held directly against thedrum by vacuum, as shown in FIG. 12. The resilience of the tape at hinge34 tends to cause the other wing 32 to spring away from the drum, oncethe knife 51 has withdrawn from contact therewith. One function offinger blade 64 is to hold exposed wing 32 against lined wing 33 andprevent its springing away. Finger blade 64 is pivotally mounted toblock 62 on pintle 65 and is subject to the action of spring 66 to urgefinger blade 64 (clockwise in the drawings) toward engagement with thetape segment 17. However, finger blade 64 is yieldable against the biasof spring 66 and hence may swing away from the drum 18, as illustratedin FIG. 5. The precise positioning of the blade 64 can be adjusted bythe thumb screw 68 which acts upon the end of lever 71 which mounts theblade 64 on the pintle 65. The desired adjustment is fixed by thumb nut67.

Accordingly, the finger blade 64 will hold the folded tape segment 17against the vacuum drum beyond the point where the knife 51 withdrawsfrom the vacuum drum 18 and the spring biased mounting of the fingerblade 64 will enable it to maintain contact with the folded tape segment17 for a short arc of movement of the vacuum drum and knife roll 20.

The finger blade 64 also holds the tape segment against the drum as theknife 51 withdraws therefrom. Inasmuch as the knife edge presses againstthe exposed adhesive face of the tape, and tends to stick thereto, itswithdrawal from the drum in the course of concurrent rotation of drums18, 19, 20 would otherwise tend to strip the tape segment off of thedrum. The finger blade 64 holds the tape segment against the drum duringthe withdrawal motion of the knife and strips the tape from the knifeedge.

Beyond the point where the finger blade 64 loses contact with the foldedtape segment 17, as shown in FIG. 6, further means are provided to holdexposed wing 32 of the tape segment against springing away from linedwing 33. Even though the vacuum of drums 18, 19 hold the lined wing 33in position, the springing away of exposed wing 32 could cause problemswhen the tape segment 17 is pressed against the undersurface of pad web15.

The added means for keeping the wings 32, 33 together comprises a hollowguide tube 72 for each drum 18, 19. Each tube 72 is curved about itsdrum 18, 19 and is substantially centered on the folded tape segment 17.Each guide tube 72 is mounted on a bracket 73 which, in turn, is mountedon a stationary part of the machine. Tubes 72 are spaced slightly fromthe drum surface to define narrow channels 74 through which the tapesegments 17 must pass en route to the point of application to theundersurface of the pad 15. Accordingly, the tape wing 32 can functionas a physical barrier or rail along which the exposed wing 32 may slideand be prevented from springing away from or unfolding with respect tolined tape wing 33.

The action of the guide 72 is desirably enhanced by making it hollow andproviding a series of air nozzles 75 along its surface which faces thedrum 18. Compressed air is fed to the hollow guide 72 through air pipe76 and the air blast or jets 77 impinge on the exposed wing 32 tomaintain the tape segment 17 folded. An air blast is preferred overfrictional contact between the wing 32 and the guide 72, thus to reducefriction and minimize the possibility that the tape will becomedislocated in the course of its transfer around the surface of the drums18, 19.

The vacuum drums 18, 19 intersect the pad web 15 opposite pressure rolls61 and the exposed adhesive wing 32 is pressed against the undersurfaceof the pads 13 and adheres thereto. The lined wings 33, which wereagainst the drums 18, 19 are now outermost, as indicated in FIG. 10. Thepad web 15 is oriented such that its plastic film component 78 isexposed to the tape 17, as shown in FIGS. 1 and 10.

As illustrated in FIGS. 1 and 2, the vacuum drum 19 is utilized to applya series of tape segments 17 along one margin of the pad web 15 and thevacuum drum 18 is utilized to apply a corresponding series of tapesegments 17 along the other side margin of the pad 15. The tape segmentsat opposite margins of the web 15 are arranged in laterally spacedpaired relation, as is illustrated in FIG. 10. The hinge lines 34 of therespective segments 17 face opposite one another and the respectivewings 32, 33 are located as indicated in this figure. The release liners41 are outermost. Accordingly, when the pads 13 are applied to a baby asshown in FIG. 9 and the release liners 41 stripped from the tape wings33, wings 33 may be swung about hinge 34 and applied to an adjacentportion of the pad, thus to interconnect opposite portions of pad 13 todiaper the baby. Inasmuch as the tape segments 17 are attached to theplastic film back 78 of the pads 13, utilization of the tape strips 17will adhere the adhesive faces of the attaching tapes to the plasticdiaper back 78 for firm adhesion thereto, no part of the tape beingadhered to a paper or non-woven or other fragile portion of the pad.

We claim:
 1. Apparatus for applying adhesive attaching tapes toworkpiece pads and comprising means for advancing to a tape folder anelongated strip of adhesive tape having an adhesive face and anon-adhesive back, tape folder means for folding the elongated tapestrip along a longitudinally extending hinge line to form substantiallyflat tape wings having their non-adhesive backs together and theiradhesive faces facing away from each other, means for applying a linerto the adhesive face of one of the wings while leaving the adhesive faceof the other wing exposed, a movable vacuum pad, means to apply thelined wing of said elongated folded tape strip to the vacuum pad so thatthe lined wing is against the pad and the adhesive face of the otherwing of the folded strip faces away from the pad, a severing tool tosever discrete folded tape segments from the folded elongated stripwhile the strip is held by vacuum on the vacuum pad, means for movingsaid vacuum pad beyond the point of severance and for applying theexposed adhesive face of said other wing to a portion of a workpiecepad, with said lined wing exposed and free for removal of the linerstrip therefrom and free for unfolding said one wing about said hingeline for subsequent application to another portion of the workpiece pad.2. The apparatus of claim 1 in combination with means for advancing anelongated workpiece pad on a path adjacent said vacuum pad.
 3. Theapparatus of claim 1 in combination with means for overcoming thetendency of said wings to spring apart about said hinge line and hencemaintain the tape segment folded during rotation of the vacuum pad anduntil the adhesive face of the said other wing engages the workpiecepad.
 4. The apparatus of claim 1 in which said vacuum pad is part of adrum and said severing tool comprises a rotary knife which coacts withthe drum to sever the tape strip therebetween
 5. The apparatus of claim1 in combination with guide means to hold the tape segment to the vacuumpad as the knife withdraws from engagement with the tape.
 6. Theapparatus of claim 5 in which said guide means comprises aspring-actuated blade mounted ahead of the knife and which engages saidtape segment during knife withdrawal.
 7. The apparatus of claim 3 inwhich the means for maintaining the tape folded comprises a guide barcurved about the path of rotation of the vacuum pad and spaced therefromto define a confined path within which the folded tape segment travelsin the course of transfer from the knife to the pad.
 8. The apparatus ofclaim 3 in which the means to maintain the tape folded comprises meansfor jetting air against the folded tape while it rotates with the vacuumpad from the vicinity of the knife to the vicinity of the pad.
 9. Theapparatus of claim 1 in which the tape folder comprises a blade againstwhich a medial portion of the non-adhesive back of the tape strip isengaged to form a crease and tape guides at the sides of said blade toforce said tape strip about the edges of the blade to dispose thesubstantially flat wings in back-to-back relation.
 10. The apparatus ofclaim 9 in which said guides comprise rollers with ribs forming grooveswithin which said wings are received.
 11. The apparatus of claim 1 inwhich said severing tool comprises a knife having an edge curved toproduce a shear cut on the tape.